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TOPIC: Readout of Volume

Readout of Volume 4 years 6 months ago #18183

  • Mungam
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Hello,
I am using a OpenDRC-DI and attached two Curryman Dacs to use it as crossover.
Is it possible to get a readout of the selected volume somewhere?
I would like to connect a Pic board and drive a display to show the volume. So I can handle I2C, SPI and Serial.

The Vol-FP only seems to convert the volume increase / decrease in IR code, so I would have to get it from the Minisharc board.
Is there any port that has the volume information?

Many thanks for any info.

Magnus
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Readout of Volume 4 years 6 months ago #18217

  • devteam
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Hello Magnus,

Unfortunately we don't have any read out pin for these.We'd have to open some level of low level firmware API to make this happening and knowing the complexity of the firmware, it's not something we're prepared to do (i.e. opening a new can of worms when it comes to tech support.. ). Sorry we're not able to help. :-(

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Readout of Volume 4 years 6 months ago #18229

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Thanks for the info.
But even if there is no dedicated output pin for the volume, it seems I found a solution:
The Vol-FP comunicates with the Minisharc via I2C, and whenever the volume is changed, the Minisharc sends the actual volume back the Vol-FP.
I am building now a small "I2C Sniffer" with an Arduino board, which will listen to the I2C bus and will show the readout on a small display.

Might be a good idea if Minidsp would offer such a display.

Magnus
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Readout of Volume 4 years 6 months ago #18235

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Mungam wrote:
...I am building now a small "I2C Sniffer" with an Arduino board, which will listen to the I2C bus and will show the readout on a small display.

May the scent of a thousand unwashed camels waft in a direction other than where you stand, sir.

In other words, May the Force be with you.

That is to say, Good luck.

Etc.

-- Jim (please keep us posted, heh)
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Readout of Volume 4 years 6 months ago #18254

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The prototype is working. I used a Chipkit Max 32 and a serial display I had laying around, works great. Should work with an Arduino, too, but haven't tried it yet. If someone wants the code and cabling (only three cables), let me know.
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Readout of Volume 4 years 6 months ago #18264

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Mungam wrote:
The prototype is working. I used a Chipkit Max 32 and a serial display I had laying around, works great. Should work with an Arduino, too, but haven't tried it yet. If someone wants the code and cabling (only three cables), let me know.
This is great. This looks like a perfect excuse for me to get back into microcontrollers; I haven't messed with them in ages. Any code, diagrams etc. you have time to post would be greatly appreciated.
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Readout of Volume 4 years 6 months ago #18270

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Attached is the code for a Chipkit. I tried it with an Arduino Leonardo, but it wasn't very reliable. It is either too slow (16 Mhz), or it has problems with the 3.3V logic level.
The Chipkit uC I used runs at 80Mhz and works with 3.3V logic.
The I2C-Bus on the Vol-FP connector is on pin 1 (SDA, red cable) and 2 (SCL, black cable). Ground is on pin 5 (also black). Connection to the Chipkit (uC32 or MAX32) is SDA -> Pin 6, SCL -> Pin 9, groud -> ground.
I put a simple error check in the code to see if messages were missed.
Maybe someone is interested to tweak the code a bit.

Magnus

If someone wonders about the gotos: This way the code is faster.
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Readout of Volume 4 years 6 months ago #18283

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Nice work - thanks again for this!

-- Jim
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Readout of Volume 4 years 6 months ago #18296

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@Mungam,

Wow.. I guess that you were not kidding when you said you'd do it.. hahah .
Good job and well done for sharing that info with the community. It's quite exciting to see this neat little setup you've done here and you deserve a lot higher than 4points of Karma for that!

Disclaimer to other readings: While miniDSP is very impressed with the great work done by someone as knowledgeable as Mungam, we would prefer not to open the tech support flood gates of firmware dev support.. We're trying our best to answer the 100's of daily questions we receive for simple audio basics (what's a low pass filter, what's a PEQ, what is Dirac..).. if we add firmware/c programming/my LCD doesn't work please help me, we're going to explode.. :-) Thanks for your understanding!

Finally, we don't have lines as good as the Jim's Camel stories so we'll stick to the "May the force be with you!" :-)

DevTeam
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Readout of Volume 4 years 6 months ago #18337

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Mungam-

What is the serial display board you used? PmodCLS?
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Readout of Volume 4 years 6 months ago #18338

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bwaslo wrote:
Mungam-

What is the serial display board you used? PmodCLS?

No, I am using an adafruit display with a serial adapter onboard I had laying around: www.adafruit.com/products/784
The PmodCLS seems to be a little slow, as it only supports 9600 baud. The adafruit board supports up to 57600 baud. But even with 57600 baud it takes approx 5ms to update the display. During that time the Chipkit can't listen to the I2C bus and might miss a message. The prgram only writes to the display after one complete message was received from the minisharc and you have to turn the volume knob very fast to miss messages, but it is possible. A better way would be to use a display that supports a faster transfer (e.g. I2C or SPI). Adafruit sells an adapter that works with 16 pin connection header displays: www.adafruit.com/products/292
Another way is to use another Arduino / Chipkit that drives the display and receives only raw data from the "sniffer" Chipkit.

I stil have a problem with the sniffer, from time to time it misses a I2C message. It seems that on the Chipkit some "background task" (maybe timer) uses the processor and during that time messages are not received correctly. As a workaround the program checks that and writes a star next to the volume to indicate that. As soon as I have a solution for it I will post it here. Maybe it works better with a ARM Arduino with 3.3V logic, but I don't have one to test it.

Magnus
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Readout of Volume 4 years 5 months ago #18495

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Hey Mungam,

Any more progress on this? I'd like to be able to tell what my volume control is set at without connecting a usb cable and laptop to the OpenDRC!

The update speed limitation could be a problem. With IR remote, I've been unable to get my OpenDRC to change reliably in less than 2dB steps (4dB with a different remote, see my post in the suggestions forum). I suspect that my remote is sending out a burst of multiple commands with each press of the volume up or down button, and if so, that could get your click reader out of whack.

But if the readout could work out with the remotes, I'd be up for cutting out a hole in the front panel of the OpenDRC to put a display in!

Thanks, Bill
Last Edit: 4 years 5 months ago by bwaslo.
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Readout of Volume 4 years 5 months ago #18496

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bwaslo wrote:
Hey Mungam,

Any more progress on this? I'd like to be able to tell what my volume control is set at without connecting a usb cable and laptop to the OpenDRC!

The update speed limitation could be a problem. With IR remote, I've been unable to get my OpenDRC to change reliably in less than 2dB steps (4dB with a different remote, see my post in the suggestions forum). I suspect that my remote is sending out a burst of multiple commands with each press of the volume up or down button, and if so, that could get your click reader out of whack.

But if the readout could work out with the remotes, I'd be up for cutting out a hole in the front panel of the OpenDRC to put a display in!

Thanks, Bill

Hello Bill,

unfortunately I had no time to investigate further. The system misses a message approx every 30-50 messages, and if a message is missed the indicated volume is usually 0,5dB wrong (high or low). It is indicated with a star (*) next to the volume reading. To get the correct reading, you just have to turn the volume knob again to get a new reading.

I am having problems with the remote, too. When using the volume knob, the volume increase / decrease is with 0,5dB steps. When using the remote, it is +- 2dB. After using the remote, the volume knob is +-2dB, too. I have to restart the unit to get the volume knob back to 0,5dB. So I think it is a firmware problem.

I'll check how many messages are missed with the remote, IMHO it was about thes same as using the volume knob.

Magnus
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Readout of Volume 4 years 5 months ago #18498

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I checked with the remote: it is as good (or bad) as the volume knob, it misses a message approx every 30-50 messages. Right now I can live with it, as the display is only 0,5 dB off if it misses a message, with the remote it is 2dB.
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Readout of Volume 4 years 5 months ago #18540

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Mungam,

I'm not familiar with LCD display hardware -- do you think something like this set would work? I like the price! The ADAFruit parts appear to be out of stock, and cost about 10x as much.

http://www.ebay.com/itm/1602-16x2-HD44780-Character-LCD-w-IIC-I2C-Serial-Interface-Adapter-Module/281317663849?_trksid=p5713.c100042.m2062&_trkparms=aid%3D555012%26algo%3DPW.MBE%26ao%3D1%26asc%3D29396%26meid%3Dd5d99c668b8f449082b20eedbb1925b3%26pid%3D100042%26rk%3D2%26rkt%3D28%26mehot%3Dpp%26sd%3D171349409569

And would the UNO32 board be usable for this (or is memory too low?). Same clock speed.
Last Edit: 4 years 5 months ago by bwaslo.
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